1. Field of the Invention
The present invention relates to optical units and, in particular, relates to an optical unit used in a vehicle lamp.
2. Description of the Related Art
A vehicle lamp, provided with an optical unit including a rotary reflector that rotates unidirectionally about the axis of rotation while reflecting light emitted by a light source, is known (see JP2010-092124). The rotary reflector is provided with a plurality of blades arranged in the circumferential direction about the axis of rotation, and each blade is provided with a reflective surface by which the light is reflected to form a desired light-distribution pattern. Light reflected by the blades is projected toward the front of the vehicle lamp through a projection lens.
When a vehicle provided with a vehicle lamp such as the one described above travels during daytime, the sunlight incident on the lamp may be condensed by the projection lens onto the reflective surfaces of the blades of the rotary reflector, and the blades may melt and be damaged.